Wide range cylindrical mirror mount with radial clamp

ABSTRACT

An improved optical mounting apparatus permits a single kinematically adjustable surface to be presented in either a horizontal or vertical orientation with respect to a support. A three point fastening system allows cylindrical optical elements of various sizes to be fastened to the kinematically adjustable surface in a horizontal orientation. The three point fastening system is removable so that when the kinematically adjustable surface is placed in a horizontal orientation transparent optical elements such as prisms can be fastened to the surface with an unobstructed optical path for a full 360° around the mounting surface. The apparatus for mounting optical elements comprises a support, base plate, a pivot member, two adjustable projections, a stage plate, and at least three removable fasteners. The base plate includes first and third opposing faces and a second face at right angles to the first and third faces. The base plate has on its first and second faces, respectively, a first and a second fastening member, for fastening the first and third opposing faces in a horizontal orientation or a vertical orientation with respect to the support. The pivot member extends from the third face of the base plate. The two adjustable projections extend from the third face of the base plate. The two adjustable projections are arcuately separated by an angle of approximately 90° with respect to the pivot member. The stage plate includes first and second opposing faces. The first face of the stage plate is spaced apart from the base plate by the pivot member and is arcuately disposed with respect to the base plate by the two adjustable projections. To lock the cylindrical optical elements of different diameters to the second face of the stage plate, at least three removable fasteners are provided.

This application is a continuation of U.S. patent application Ser. No.08/878,466, filed Jun. 18, 1997, entitled "Wide Range Cylindrical MirrorMount With Radial Clamp", now U.S. Pat. No. 5,847,885, which isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to an apparatus for mountingmultiple optical elements, such as mirrors, beam splitters, lenses,gratings, filters and the like. More particularly, the present inventionrelates to an optical mount which holds cylindrical and planar opticalelements at angular offsets from either of two orthogonal orientations.

2. Description of Related Art

The use of adjustable mounting apparatus for supporting opticalcomponents, such as mirrors, beam splitters, lenses, gratings, and thelike, is known. The use of adjustable mounting or clamping devices is acommon technique in the field of experimental optics. Such mounts areused to position optical elements, such as mirrors, beam splitters,lenses and gratings, light sources and other optical devices. Sincethese devices do not conform to a standard set of dimensions, each mayrequire its own mount. The requirements are further complicated by thefact that each optical element has to be positioned at a preciseorientation and location to each other and to the optical bench.

Optical mounts comprise a pair of generally parallel plates, of whichone of the plates is fixed to a surface or base and the other plate isadjustably suspended from the first plate. The second plate may bemounted using a "six-point suspension," where adjustment of theperpendicular distance between the plates at each of the threesuspension points can provide for fine adjustments to the orientation ofthe second plate. The ability to perform minute adjustments, on theorder of a few arc seconds, to the orientation of an optical element isparticularly necessary, in applications such as interferometry,holography, and optical communication where precise collumnation of alaser beam(s) is necessary.

Typically, optical mounts incorporating a "six-point suspension" systemare fabricated from metal, machined to close tolerances, and are thusexpensive. Many such mounts are required in even the most elementaryset-ups. Compounding the costs associated with precision optical set-upsis the fact that each mount typically requires an expensive adaptor tohold optical elements of different shapes and sizes.

Thus, there is a need for a optical mount that is inexpensive andcapable of accommodating various shapes and sizes of optical elements.There is a further need for an optical mount which permits fineadjustments to the mounting surface such as those associated with a"six-point suspension."

SUMMARY OF THE INVENTION

An object of the invention is to provide an optic mount that can hold awide range of shapes and sizes of optic elements, without the use ofspecial adaptors or a dedicated seat.

Another object of the invention is to provide a single mount capable ofpresenting either a horizontal or vertical mounting surface for anoptical element.

A further object of the invention is to provide a kinematic adjustmentmechanism that can precisely adjust the mounting surface in either thehorizontal, or the vertical orientation to facilitate the precisealignment of an optical set-up.

According to the present invention, an optical mounting apparatus isprovided for mounting of a plurality of optical elements on a support.The apparatus includes: a block, a first fastener, a compressive member,a first pair of support members and a first pair of fasteners. The blockincludes a first and a second face which are joined along an edge. Thefirst fastener is defined by the second face, and is aligned on atransverse axis parallel to the first face. The compressive member isdefined to engage the first fastener and to move along the transverseaxis from an open position displaced from the second face to a closedposition next to the second face. The first pair of fasteners is definedby the first face. Each one of the first pair of fasteners is positionedon opposite sides of the transverse axis. The first pair of fastenersengages the first pair of support members to provide for a compressiveclamping of a cylindrical optic element between the first pair ofsupport members and the compressive member in the closed position.

According to another embodiment of the invention, an apparatus foradjustable mounting of a plurality of optical elements on a support isprovided. The apparatus comprises a block, a first and second supportattachment and a fastening system. The block includes a first, second,third and fourth face. The second face joins the first face along anedge. The third face is orthogonal to the first face and opposite thesecond face. The fourth face is parallel to the first face and joins thesecond and third faces. The first support attachment is defined by thethird face to provide for fastening of the block to the support in afirst orientation in which the first face is parallel to a longitudinalaxis of the support. The second support attachment is defined by thefourth face and provides for fastening of the block to the support in asecond orientation in which the first planar face is orthogonal to thelongitudinal axis of the support. The fastening system provides for theattachment of an optical element to the first planar face of the block.The optic elements include cylindrical mirrors and beam splitters.

According to a further embodiment of the present invention, an opticalmounting apparatus is provided which permits a single kinematicallyadjustable surface to be presented in either a horizontal or verticalorientation with respect to a support. A three point fastening system isdisclosed which allows cylindrical optical elements of various sizes tobe fastened to the kinematically adjustable surface in a horizontalorientation. The three point fastening system is removable so that whenthe kinematically adjustable surface is placed in a horizontalorientation transparent optical elements such as prisms can be fastenedto the surface with an optical path which is unobstructed for the full360° around the mounting surface.

The apparatus for mounting optical elements includes a support, baseplate, a pivot member, two adjustable projections, a stage plate, and atleast three removable fasteners. The base plate includes first and thirdopposing faces and a second face at right angles to the first and thirdfaces. The base plate has on its first and second faces, respectively, afirst and a second fastening member, for fastening the first and thirdopposing faces in a horizontal orientation or a vertical orientationwith respect to the support. The pivot member extends from the thirdface of the base plate. The two adjustable projections extend from thethird face of the base plate. The two adjustable projections arearcuately separated by an angle of approximately 90° with respect to thepivot member. The stage plate includes first and second opposing faces.The first face of the stage plate is spaced apart from the base plate bythe pivot member and is arcuately disposed with respect to the baseplate by the two adjustable projections. To lock the cylindrical opticalelements of different diameters to the second face of the stage plate,at least three removable fasteners are provided.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of the optical mount positioned as a facemount and holding a larger diameter optical element.

FIG. 2 is a perspective view of the optical mount positioned as a facemount and holding a small diameter optical element.

FIG. 3 is a perspective view of the optical mount positioned as a basemount and holding an optical element on the base.

FIG. 4 is an exploded sectional view of the optical mount shown in FIG.2.

FIG. 5 is a side view of the optical mount.

FIG. 6 is a back view of the optical mount.

FIG. 7 is an item view of the optical mount taken along line 7--7 of theFIG. 5.

FIG. 8 is a front view of the optical mount.

DETAILED DESCRIPTION

The optical mount of this invention allows for mounting of opticalelements on a kinematically adjustable surface, which can be orientedeither horizontally or vertically with respect to a support surface. Inthe horizontal configuration, cylindrical optical elements of varyingdiameters are firmly attached to the kinematically adjustable face plateby a simple three-point fastener system. The fasteners can berepositioned to accommodate optics of varying diameters. In thehorizontal configuration, optical elements of varying diameters andgeometries can be fastened to the kinematically adjustable horizontalstage plate by either the three-point fastening system or by anadhesive. Thus, a versatile inexpensive optical mount is disclosed forholding optical elements of a variety of sizes and shapes. The opticalelements which may be held include mirrors, prisms, beam splitters,gratings, etc.

FIGS. 1-2 are perspective views of the optical mount oriented to providea kinematically adjustable surface which is vertically oriented inrespect to X-Z groundplane. A large diameter optical element is shownmounted on the vertical surface in FIG. 1 and a small diameter opticalelement is shown mounted on the vertical surface in FIG. 2. As shown inFIGS. 1-2, the optical mount comprises base plate 20, stage plate 22,support column 24, kinematic adjustment screws 26, 28, 30, three-pointfasteners 34, 36, 38 and stage-to-base plate tension assemblies of whichthe portions 46A-B, 48A-B, and 50A-B, are shown.

In FIG. 1, a specific embodiment is shown in a one-inch diameter opticalelement 32, e.g., a reflective mirror, is shown fastened to the exteriorface 52 of stage plate 22. The optical mirror 32 rests on three-pointfastener support pins 36 and 38 which screw into threaded holes 40 and42 respectively, in stage plate 22. Holes 40 and 42 are positioned belowthe midpoint of optical element 32 and on either side of a vertical linerunning through the centerline of the thumbscrew 34. The holes may besymetrically or asymetrically displaced on either side of thecenterline. The holes are positioned so that an optical element 32 canbe clamped by the compressive action of thumbscrew 34. In an embodimentthe holes are positioned so that an arcuate portion of an optic elementwill extend above the upper surface of stage plate 22, so that it can beclamped against support pins 36-38 by the thumbscrew 34. In an alternateembodiment, the thumbscrew 34 includes an assymetric washer with anextension that rides on face 52 and allows an optic which does notextend beyond the upper surface of stage plate to be compressivelyclamped by the thumbscrew and washer against support pins 36-38. In theembodiment shown in FIG. 1 the optical element is clamped againstsupport pins 36 and 38 by the compressive action of thumbscrew 34, whichis also threaded into the stage plate 22 along a longitudinal axisparallel to the plane of exterior face 52 of the stage plate. As thethumbscrew is moved toward the stage plate into the closed position, itcompressively clamps the optic element.

As will be obvious to those skilled in the art, the three-point mountingsystem can be implemented on a solid block, a kinemetic mount, arotational mount, or a translational mount. The plurality of hole pairs40-42 and 150-152 in which support pins 36-38 can be mounted can bepositioned anywhere on face 52 provided only that the support pins arepositioned on either side of the longitudional axis of the thumbscrew34. Other forms of three-point fasters can be utilized beyond thesupport pin and thumbscrew combination shown, without departing from theteaching of this invention. These other fasteners include: spring clips,snaps, deformable plugs, pins, arcuate clips, etc.

In FIG. 2, an alternate embodiment is shown in which a half-inchdiameter optical element 44, e.g., a half-inch mirror is shown rigidlyclamped to exterior face 52 of stage plate 22 by the three-pointfastening system comprising screws 36 and 38 and thumbscrew 34. Screws36 and 38 are in this embodiment shown threaded into a second set ofholes 150 and 152 respectively, in the stage plate. These holes are alsopositioned below the midpoint of the half-inch optical element 44 and oneither side of a vertical line running through the midpoint of thatoptical element. The holes are positioned above the first set of holes40-42 so that an arcuate portion of the smaller diameter half-inchoptical element 44 also extends above the upper-most surface of stageplate 22. Thumbscrew 34 asserts a radial force against optical element44 and holds it in frictional contact with fasteners 36 and 38.

As further shown in FIGS. 1-2, stage plate 22 is elastically fastened tobase plate 20 by means of tensioning members of which 46A-B, 48A-B and50A-B are referenced. In this preferred embodiment, two springs are usedto elastically bias the stage plate toward the base plate. The springspass from the base plate through holes 46A and 46B in the stage platewhere they are held in the extended position by retaining pins 50A-Bpositioned in recessed slots 48A-B. The recessed slots allow the springto be anchored to the stage plate without breaking into the plane of theexterior face 52 of stage plate 22. It will be appreciated that othertensioning means may be used to draw the stage plate towards the baseplate, including spring metal clips, magnets, and adhesively fastenedresilient elastomers.

Counteracting the tensioning force of the springs which tends to drawthe stage plate towards the base plate are kinematic adjustment members26, 28, and 30. In this preferred embodiment, these adjustment membersare shown as thumbscrews. As will be shown in greater detail in FIG. 4,these thumbscrews extend through threaded holes in the base plate tokinematic points of contact with the stage plate. Thumbscrew 26 allowsfor relative positioning along the Z axis of the stage plate withrespect to the base plate. Thumbscrew 28 allows for arcuate movementabout axis parallel to the X axis of the stage plate with respect to thebase plate. Thumbscrew 30 allows are arcuate movement about axisparallel to the Y axis of the stage plate with respect to the baseplate. Thus, another feature of the optic mount is that it provides afinely adjustable vertical mounting face suitable for fastening opticalelements with the precision required for applications such as holographyor interferometry.

A further feature of the optic element is shown in FIG. 3. The opticmount has been repositioned with respect to column 24 to provide akinematically adjustable surface horizontal to the X-Z base plane formounting an optic element. Column 24 has been fastened by means of athreaded member to the back side of base 20. Three-point fasteners 34,36, 38, have been removed from threaded holes 102, 40, and 42,respectively. Thus, an unobstructed horizontal planar surface 52 isavailable for mounting an optic element. In this case the optic elementshown is a prism 80 which is fastened to exterior face 52 by an adhesivestrip 84. In this orientation, kinematic adjuster 26 allows for relativemovement along the Y axis of stage plate 22 with respect to base plate20. Kinematic element 28 allows for arcuate movement about axis parallelto the X axis of the stage plate with respect to the base plate.Kinematic adjuster 30, (not shown) allows for arcuate movement about theaxis parallel to the Z axis of stage plate 22 with respect to base plate20.

The fact that the three-point fastening system, when removed, presents aflat, i.e., planar surface is advantageous, in that it allows the samemount to be utilized for mounting a different class of optic elements.These include: i.e., prisms, corner cubes, beam splitters, etalons,detectors, light sources, gratings, etc. This is in contrast to theprior art approach in which surface 52 is aplanar, i.e., has acounterbore for compressively clamping cylindrical optic elements to theface. The aplanar prior art surfaces do not allow for the mounting opticelements such as prisms, corner cubes, detection sources etc. whichrequire a flat, unobstructed mounting surface. The present inventionprovides such a flat mounting surface with an optically unobstructedpath for a full 360° around the optic element. Thus, prisms, cornercubes, beam splitters can be mounted to face 52 in either the horizontalorientation shown in FIG. 3 or the vertical orientation shown in FIGS.1-2.

FIG. 4 is an exploded isometric view of the optic mount in theorientation shown in FIG. 2. The components of the tension system, thekinematic adjustment system, the three-point fastener, and thecolumn-to-base plate fastener are each shown.

The tensioner system comprises springs 104, 106; base plate holes 46C-D,and associated pin slots 48A-D; and retaining pins 50A-D. Stage plate 22is held in tension against base plate 20 by means of both springs 104and 106. Springs 104 and 106 have hooks on either end. The hooks onsprings 104 and 106 allow those springs to be held below the plane ofexterior face 52 of the stage plate by retaining pins 50A-B,respectively. The springs 104 and 106 are then drawn through holes46D-C, respectively in base plate 20. The springs are stretched to thepoint where retaining pins 50D-C, can be inserted through the hooks inthe ends of springs 104-106. The springs are then released and retainingpins 50B-C are drawn into pin slots 48D-C, respectively. The remainingtension on each of springs 104 and 106 provide the tensioning fordrawing stage plate 22 toward base plate 20.

The kinematic adjustment assembly comprises kinematic adjustments screws26-30, threaded base plates hole 108-112, and kinematic stage platecontact points 114-118. Kinematic adjustments screws 26, 28 and 30 havehemispherical tips. These screws are threaded through correspondingthreaded base plate holes 108, 110, and 112 and contact, respectively,stage plate kinematic mounts 114, 116, and 118. The ball tip ofkinematic adjustment screw 26 contact stage plate 22 at kinematic mount114. Kinematic contact point 114 is a conically shaped detent whichprovides three points of contact with the tip of adjustment screw 26. Inan alternate embodiment if no relative positioning along the Z axis ofthe stage plate is desired, a ball bearing may be substituted forthumbscrew 26. The ball bearing would rest in contact point 114 andcontact the opposing interior face of base 20, thereby providing a pivotpoint for the two plates 20-22. The hemispherical tip of kinematicadjustment screw 28 contact stage plate 22 at a single point of contactprovided by flat bottom detent 116. The hemispherical tip of kinematicadjustment screw 30 contacts stage plate 22 at two points of contactprovided by V-shaped slotted detent 118 in stage plate 22. Thus, sixpoints of contact are provided by the combination of thumbscrews 26-30with kinematic contact points 114-118. This allows for the preciseadjustment about the X, Y and Z axis of the stage plate with respect tothe base plate.

The three-point fastening assembly discussed above is shown comprisingbase screws 36 and 38 and thumbscrew 34. The base screws 36 and 38 arethreaded into the plurality of holes on the stage plate face 52. Theseholes are positioned to accommodate varying diameters of optic elementsand to position an arcuate upper portion of each optic element above theplane of the upper surface of stage plate 22. The protrusion of theoptic above the plane of the upper face of stage plate 22 allows for athumbscrew 34 to radially clamp the optic against three-point fasteners36 and 38.

Base 22 may be oriented in one of two orthogonal orientations withrespect to column 24. Column 24 has a threaded tip 100 which whenfastened to threaded hole 120 in base plate 20 provides a kinematicallyadjustable vertical surface for the mounting of optics of variousdiameters. Alternately, when column 24, and specifically threaded tip100, is threaded into hole 122 on the back surface of base plate 20 thenface 52 is oriented parallel to the longitudinal axis of column 24 and akinematically adjustable horizontal surface is provided for mounting theoptic element. When fasteners 34-38 are removed, an optic elementmounted on the horizontal surface 52 is optically unobstructed by anyobjects above the plane of mounting surface 52, as shown in FIG. 3.

FIGS. 5-8 show side, back, base and front views, respectively of theoptic mount in a vertical mount orientation. FIG. 5 shows the one-inchdiameter optical element 32 fastened to stage plate 22 by three-pointfastening system comprising thumbscrews 34-38. The stage plate is drawntowards the base plate by springs, of which spring 104 is shown. Thestage plate is arcuately positioned with respect to the base plate bymeans of kinematic adjustment screws of which 26-28 are referenced. Thebase plate is shown fastened to column 24. FIG. 6 shows a back view ofthe optic mount and the three kinematic adjustment screws 26-30. Themounting hole 122 for column 24 is shown. As discussed above, attachmentof the column to this hole orients the mounting surface 52 of stageplate 22 horizontally. The portion of tension assembly comprising holes46C-D, slots 48C-D, and retaining pins 50C-D is shown. FIG. 7 is a baseview of the optic mount taken along line 7--7 in FIG. 5. The basemounting hole 120 for column 24 is shown. Attachment of the column tothis hole orients mounting surface 52 of stage plate 22 vertically.Kinematic adjustment screws 26 and 30 are referenced. The lowerthumbscrews 36 and 38 for attachment of the optic element to the stageplate are referenced. FIG. 8 is a front view of the optic mount. Thethreaded hole pairs 40-42 and 150-152 for the one-inch and half-inchoptic elements are shown. The portion of the tension assembly comprisingholes 46A-B, slots 48A-B, and retaining pins 50A-B is shown.

Although the foregoing invention has been described in detail forpurposes of clarity of understanding, it will be obvious that certainmodifications may be practiced within the scope of the appended claims.

What is claimed is:
 1. An apparatus for mounting an optical element,said apparatus comprising:a block including a first planar face and asecond face, and said second face joining said first planar face; afirst fastening means aligned on an axis parallel to said first planarface; a compressive member defined to engage said first fastening meansand to move along the axis from an open position displaced from thesecond face to a closed position proximate the second face; a first pairof support members; a first pair of fastening means defined by saidfirst planar face and each one of said first pair of fastening meansengaging a corresponding one of said first pair of support members toprovide for a compressive clamping of the optical element between saidfirst pair of support members and said compressive member in the closedposition.
 2. The apparatus of claim 1, further comprising:a second pairof fastening means defined by said first planar face and each one ofsaid second pair of fastening means engaging a corresponding one of saidfirst pair of support members to provide for a compressive clamping of asecond optical element between said first pair of support members andsaid compressive member in the closed position.
 3. The apparatus ofclaim 2, wherein:the first pair of fastening means includes:a first pairof apertures defined by said first planar face and each of the firstpair of apertures orthogonal to said first planar face; the second pairof fastening means includes:a second pair of apertures defined by saidfirst planar face and each of the second pair of apertures orthogonal tosaid first planar face; and the first pair of support members includes:apair of fastening pins each frictionally retained within a correspondingone of the first and the second pairs of pair of apertures.
 4. Theapparatus of claim 3, wherein:each one of said first pair and saidsecond pair of apertures comprise a threaded bore; and each one of saidpair of fastening pins includes a thread suitable for rotatably engagingthe threaded bore of a corresponding one of said first and said secondpairs of apertures.
 5. The apparatus of claim 1, wherein:the firstfastening means defined by said second face, comprises a threaded bore;and the compressive member comprises a bolt including a thread suitablefor rotatably engaging the threaded bore of said first fastening means.6. The apparatus of claim 1, wherein:said block further comprises athird and a fourth face, and said third face orthogonal to said firstplanar face and opposite said second face, and said fourth face parallelto said first planar face and joining said second face and said thirdface; a first column attachment means defined by said third face, andsaid first column attachment means aligned to provide for the fasteningof said block to a column in a first orientation in which said firstplanar face is parallel to a longitudinal axis of the column; and asecond column attachment means defined by said fourth face, and saidsecond column attachment means aligned to provide for the fastening ofsaid block to the column in a second orientation in which said firstplanar face is orthogonal to the longitudinal axis of the column.
 7. Theapparatus of claim 6, wherein:said first column attachment means andsaid second column attachment means comprise respectively a firstthreaded bore and a second threaded bore.
 8. The apparatus of claim 6,wherein:said first attachment axis of said first column attachment meansintersects said second attachment axis of said second column attachmentmeans.